In mobile radio receivers, received radio frequency signals are frequently a combination of signals, some received directly from a transmitting antenna and some reflected from stationary and/or moving objects. In the worst case, the received signals from the direct and alternate path signals combine at the receiving antenna to cause destructive interference. Such interference makes decoding of the signals more difficult. Further, in some instances, interference can reduce the amplitude of the received signals to a level that is too low for reliable decoding by the receiver. Such amplitude reduction is sometimes referred to as multi-path fading.
One technique for improving signal reception under multi-path fading and weak signal conditions includes the use of multiple antennas and receiver circuits in an antenna diversity system. In a multi-chip antenna diversity system, multiple tuner circuits that are tuned to particular frequencies receive program content (channel information) from more than one direction or at slightly different positions. Such antenna diversity systems typically include processor circuitry configured to combine signals from the different tuners to produce an enhanced signal or to select a particular signal from a tuner having the strongest signal output.
Diversity reception makes use of statistically independent signal streams to reduce the impact of severe multipath-related channel fading. However, digital communications between the multiple tuner circuits and associated processing circuitry can radiate spectral energy at radio frequencies to which one or more of the tuner circuits are tuned, further complicating signal reception.